I was one of the 300,000-plus people in the People’s Climate March in New York on September 21 – and like many others there, it had been a long time since I joined a march. I couldn’t pass up the opportunity to be part of a big crowd, all sharing a growing feeling of alarm over patterns of climate change, and deep dismay over patterns of denial among those who could and/or should know better.

The low clouds held back except for a brief spatter of rain, and the mood held too: a lovely parade buoyancy, and a palpable excitement at being part of a visible expression of something we all cared about. I went on one of dozens of buses from Philadelphia organized by 350.org, carrying my handmade sign, saying WAKE UP. My partner for the day was Diane Burko, an artist who has been making powerful paintings and photographs documenting the melting of glaciers and other effects of climate change. Diane has traveled to the Arctic Circle, Greenland, and Antarctica, and to scientific conferences to speak about her work.

This group’s slogan was Give Bees a Chance

The parade had seven thematic groupings, starting with FRONTLINES OF CRISIS, FOREFRONT OF CHANGE and ending with the inclusive TO CHANGE EVERYTHING, WE NEED EVERYONE. Diane and I joined the group behind the banner THE DEBATE IS OVER, whose float was a giant rolling blackboard with drawings charting rising CO2 and ocean temperatures. We were surrounded by scientists—old and young, men and women, of many backgrounds, and many with their children—representing fields from geology to psychoanalysis.

Because the turnout was so much higher then expected – estimates had been around 100,000 beforehand – the street backed up with participants, and those of us in the back stood for several hours before actually marching. Pizzas were delivered, snacks and water were shared. Finally, we set off down Central Park West, walking with people who had lost homes to Katrina and Sandy, young activists, old activists, dignitaries, working people, stilt walkers, musicians, people representing Pacific island nations whose very land is in danger of disappearing under rising seas.

The Statue of Liberty in rising waters, wearing a life jacket

The parade ended at 11th Avenue, near the Hudson River. It’s not far from here, I realized, that a scene takes place toward the end of Jennifer Egan’s novel A Visit from the Goon Squad. In Egan’s brilliant vision of the ways we are changed by technology and other forces, climate change has become part of the background of city life: a few decades from now, on a warm day in February, a young family gathers with others on the ramparts of the giant sea wall that’s been built to keep the rising waters out of New York. Climbing up to watch the sunset from there has become a new tradition, since the view has been blocked out by the wall.

What will we have to face as a result of the climate change that has already been set in motion? People whose cities have the resources to build sea walls will be the lucky ones. We need to acknowledge what scientists are telling us, and we need help from artists and others to visualize what’s happening now, and to imagine what’s in store. We need to wake up.